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Update bash.md

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Angus Hollands 2020-04-20 11:21:31 +01:00 committed by GitHub
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@ -1,4 +1,4 @@
--- (---
title: Bash scripting title: Bash scripting
category: CLI category: CLI
layout: 2017/sheet layout: 2017/sheet
@ -217,7 +217,7 @@ echo ${STR^^} #=> "HELLO WORLD!" (all uppercase)
| `${FOO:-val}` | `$FOO`, or `val` if unset (or null) | | `${FOO:-val}` | `$FOO`, or `val` if unset (or null) |
| `${FOO:=val}` | Set `$FOO` to `val` if unset (or null) | | `${FOO:=val}` | Set `$FOO` to `val` if unset (or null) |
| `${FOO:+val}` | `val` if `$FOO` is set (and not null) | | `${FOO:+val}` | `val` if `$FOO` is set (and not null) |
| `${FOO:?message}` | Show error message and exit if `$FOO` is unset (or is null) | | `${FOO:?message}` | Show error message and exit if `$FOO` is unset (or null) |
Omitting the `:` removes the (non)nullity checks, e.g. `${FOO-val}` expands to `val` if unset otherwise `$FOO`. Omitting the `:` removes the (non)nullity checks, e.g. `${FOO-val}` expands to `val` if unset otherwise `$FOO`.